Lucia Marinelli

The evaluation of the microbial safety of fresh ready-to-eat vegetables produced by different technologies in Italy

Aims:  The study was performed to evaluate the safety of whole and RTE vegetables and to investigate the effectiveness of different preventive strategies for the quality assurance of RTE vegetables collected from three Italian production systems. Producer 1, applied a strict system in compliance with GAP‐ GMP – HACCP, Producer 2 used chlorine disinfection at a second washing step, and Producer 3 using a physical microbial stabilization.

Microbiological air quality in an urban solid waste selection plant

Background: Exposure to bioaerosols may pose health risks to workers operating in the processing of Urban Solid Waste (USW). The aim of this study is to evaluate microbiological air quality within an USW selection facility. Methods: Nine sampling points in an USW selection plant situated in central-southern Italy were selected. One outdoor sampling point provided the background data. Sampling was performed on a yearly basis (2005 ‐ 2009) upon request by the management of the selection plant. Total Mesophilic Counts (TMC), as well as fungal and Gram-negative concentrations were determined. Results: The highest viable fungal particles concentrations (medians) were found in waste delivery areas (about 20000 CFU/m 3), while the lowest were found in the control rooms (485 ‐ 967 CFU/m 3). TMC (median) was highest (6116 CFU/m 3) at the delivery pit, followed by the machine shop (3147 CFU/m 3), where no waste processing takes place. Medians of Gram-negative bacteria are below the suggested Occupational Exposure Limit of 1000 CFU/m 3, although this limit was exceeded at several single time-points in the waste delivery areas, and also in a personnel resting room. The lowest Gram-negative contamination was found in the control rooms (medians <1 CFU/m 3). Conclusions: Some areas within a USW selection plant act as internal sources of contamination towards those areas where partially processed waste, or no waste at all, is present. Well-designed air flows, or carefullythought positioning of areas that are not directly involved in waste processing are necessary and effective in obtaining satisfactory microbiological air quality, provided that personal protection practices are strictly enforced.

Legionella control in the water system of antiquated hospital buildings by shock and continuous hyperchlorination: 5 years experience

BackgroundTo control the presence of Legionella in an old hospital water system, an integrated strategy of water disinfection-filtration was implemented in the university hospital Umberto I in Rome.MethodsDue to antiquated buildings, hospital water system design and hospital extension (38 buildings), shock hyperchlorination (sodium hypochlorite, 20–50 ppm of free chlorine at distal points for 1–2 h) followed by continuous hyperchlorination (0.5-1.0 mg/L at distal points) were adopted, and microbiological and chemical monitoring of the water supply was carried out in the university hospital (December 2006-December 2011).ResultsOverall, 1308 samples of cold <20°C (44.5%), mixed ≥20°C ≤ 45°C (37.7%) and hot >45°C (17.8%) water were collected, determining residual free chlorine (0.43 ± 0.44 mg/L), pH (7.43 ± 0.29) and trihalomethanes (8.97 ± 18.56 μg/L). Legionella was isolated in 102 (9.8%) out of 1.041 water samples without filters (L. pneumophila sg 1 17.6%, L. pneumophila sg 2–14 28.4%, L. non pneumophila 53.9%), and in none of the 267 samples with filters. Legionella was recovered in 23 buildings out of 38 and 29 samples (28.4%) exceeded 103 cfu/L. When considering the disinfection treatment Legionella was isolated: before shock hyperchlorination (21.1%), 15 days after shock hyperchlorination (7.8%), 30 days after shock hyperchlorination (3.5%), during continuous hyperchlorination (5.5%) and without continuous hyperchlorination (27.3%). Continuous hyperchlorination following the shock treatment achieved >70% reduction of positive samples, whereas no continuous hyperchlorination after shock treatment was more frequently associated to Legionella isolation (OR 6.41; 95% CI 3.10–13.26; p <0.001). Independent risk factors for Legionella isolation were: residual free chlorine <0.5 mg/L (OR 13.0; 95% CI 1.37 – 123.2; p <0.03), water T° ≥20°C ≤ 45°C (OR 12.0; 95% CI 1.28 – 111.48; p <0.03) and no continuous hyperchlorination after shock treatment (OR 10.3; 95% CI 1.06 – 100.05; p <0.05).ConclusionsShock and continuous hyperchlorination achieved significant Legionella reduction, but effective chlorine levels (>0.5 < 1.0 mg/L) deteriorated water quality (organoleptic and chemical). However, shock and continuous hyperchlorination remains a valid-term option in old buildings with no water system rational design, managing problems due to hospital extension and absence of a proper hot water recirculation system.

Ready-to-eat vegetables production with low-level water chlorination: an evaluation of water quality and of its impact on end products

INTRODUCTION We evaluated the microbiological impact of low-level chlorination (1 ppm free chlorine) on the production of ready-to-eat (RTE) vegetables by monitoring the microbiological quality of irrigation and processing water in two production plants over a 4-season period, as well as the microbiological quality of unprocessed vegetables and RTE product. Water samples were also characterized in terms of some chemical and physico-chemical parameters of relevance in chlorination management. MATERIALS AND METHODS Both producers use water with maximum 1 ppm free chlorine for vegetables rinsing, while the two processes differ by the number of washing cycles. RESULTS AND CONCLUSIONS Salmonella spp and Campylobacter spp were detected once in two different irrigation water samples out of nine from one producer. No pathogens were found in the vegetable samples. As expected, the procedure encompassing more washing cycles performed slightly better in terms of total mesophilic count (TMC) when comparing unprocessed and RTE vegetables of the same batch. However, data suggest that low-level chlorination may be insufficient in preventing microbial build-up in the washing equipment and/or batch-to batch cross-contamination.

Factors influencing persistence of Legionella pneumophila serogroup 1 in laboratory cocultures

BackgroundRisk for infections from Legionella pneumophila for immunocompromised individuals increases greatly when this species is present within the biofilm of the water distribution systems of hospitals or other health facilities. Multiplication and persistence of Legionella may dependent also upon planktonic growth in alternative to sessile growth. Here we compared the persistence of L. pneumophila serogroup 1 in experimental planktonic co-cultures subsided with iron, Pseudomonas aeruginosa and other non Legionella bacteria (quantified as Heterotrophic Plate Count, HPC at 37°C), isolated from drinking water sources of a large hospital.ResultsConcentrations of L. pneumophila showed a decreasing pattern with incubation time in all co-cultures, the degree of reduction depending on the experimental treatment. In co-cultures with added P. aeruginosa, no L. pneumophila was detectable already after 4 days of incubation. In contrast in co-cultures without P. aeruginosa, HPC but not iron were significant factors in explaining the pattern of L. pneumophila, although the HPC effect was different according to the incubation time (HPC x time interaction, p <0.01).ConclusionsOur results highlight the need of controlling for both HPC and metal constituents of the water systems of buildings used by individuals at particular risk to the effects of Legionella exposure.

Prevalence of Staphylococcus aureus colonization and antibiotic susceptibility: A survey among biomedical students

Staphylococcus aureus is a major human pathogen, causing both hospital and community-acquired infections. It is responsible for 25% of healthcare-associated infections and contributes substantially to morbidity and cost of hospital stays. The source of many of these infections is thought to be the patients’ endogenous flora. The ecological niche of S. aureus is the anterior nostrils, and 25e30% of individuals are colonized at a given time. Numerous studies have linked nasal carriage of S. aureus with increased risk of infection with S. aureus in various settings. A study conducted in central Italy to establish the rates of nasal carriage of S. aureus and antibiotic susceptibility patterns in the community showed that the prevalence of nasal carriage of S. aureus was 30 5%, with only one subject identified as a carrier of meticillin-resistant S. aureus (MRSA) (prevalence 0 12%). In another Italian study conducted in injection drug users, the prevalence of nasal colonization with S. aureus was 8.83%, and 12.5% of isolates were found to be meticillin resistant. Recently, concern has increased regarding the spread of MRSA in the community and schools. Students with weakened immune systemsmay be at risk formore severe illness if

Temporal pattern of microbial indicators of ready-to-eat rocket salads during shelf life

INTRODUCTION From 2001-2009 there have been numerous community alerts and notifications about the rocket salad produced in Italy and distributed in Europe. Our study describes the evolution of the microbial quality of ready to eat rocket salad during shelf life among three different Italian producers. MATERIAL AND METHODS Total Mesophilic Count (TMC) and Escherichia coli (EC) count were measured in 248 samples. We used Wilcoxon test to compare the median values of TMC and EC counts and Kruskal Wallis test to compare the producers. RESULTS The TMC and EC values differed among producers at the stages of raw material and in the finished product (Kruskall Wallis test, p < 0.05). The evolution of bacterial charges had significant differences among producers at expiration date (Wilcoxon test, p < 0.05). More than half of the samples (54.8%) exceed reference standard for TMC after 48 h from packaging. CONCLUSION Differences among producers may linked to the different minimal processing technologies adopted after harvesting.

Knowledge, attitude and behaviour toward MRSA: Results from a survey among biomedical students and the general population

BackgroundThe spread of methicillin-resistant Staphylococcus aureus (MRSA) is of increasing concern, especially for particular populations such as school or university students. This study compares the knowledge, attitudes and behaviour towards MRSA skin infections between a group of medical and public health students who attend courses and practice in a teaching hospital setting to a general population group represented by their family members, cohabitants and friends.MethodsIn the period March–April 2009, a survey was conducted on 166 students and their cohabitants (182). After informed consent, a self-administered questionnaire was given to each participant, containing questions concerning socio-demographic (age, gender, educational level, job activity) and leisure-time items (physical activity) as well as knowledge regarding the localisation, symptoms, means of transmission of a MRSA infection, susceptible groups, therapeutic and diagnostic aspects, and the correct behaviour for preventing transmission to others. All the students were belonging to medical and public health Technician school in a teaching hospital setting.ResultsStudy participants were 116 biomedical students and 182 family members, cohabitants and friends. The comparison among the levels of knowledge revealed a significant difference between the two groups. One-third (30.1%, 50/166) p = 0,006 of biomedical students ignore the anatomical site of MRSA infection while 20.5% (34/166) do not known the determinants involved in increasing the risk and ignore the possible development resistance to the antibiotics of S. aureus causing intractable infection (p = 0,001). Regarding attitude and behaviour toward MRSA, the distribution of answers were statistically different among the two groups in the questions regarding the diagnosis, the choice of the person to be seen if infected and the question on the prevention measures to be adopted in case of infection. Moreover, more than half of the participants are willing to pay 100 € (the maximum amount proposed) to have the best care in case of staph infection.ConclusionMost of the participants had a poor or even a very poor knowledge of the pathogen, mechanism of transmission, risk determinants and preventive measures. There is a strong need to implement targeted educational programs within current university curricula and for the general population.

Microbiological safety of glasses dispensed at 3D movie theatres

Recent popularity of three-dimensional movies raised some concern about microbiological safety of glasses dispensed into movie theatres. In this study, we analysed the level of microbiological contamination on them before and after use and between theatres adopting manual and automatic sanitation systems. The manual sanitation system was more effective in reducing the total mesophilic count levels compared with the automatic system (P < 0.05), but no differences were found for coagulase-positive staphylococci levels (P = 0.22). No differences were found for mould and yeast between before and after levels (P = 0.21) and between sanitation systems (P = 0.44). We conclude that more evidences are needed to support microbiological risk evaluation.

A New Biosensor to Enumerate Bacteria in Planktonic and Biofilm Lifestyle

Remarkable interest for human health concerns the microbiological risk assessment due infections by bacteria possessing the ability to adhere to host cell or abiotic surfaces as well as to live in aggregated and biofilm lifestyle. Biofilm is multicellular bacterial community held together by a self-produced extracellular matrix in response to several factors. These factors may include recognition of specific or non-specific attachment sites on cell surfaces, electrostatic interactions on abiotic surfaces, nutritional cues, or in some cases, exposure to stress conditions in the environment as well as into the host. Biofilm lifestyle is comparatively more common than the planktonic one and it has been shown that biofilm plays a crucial role in human health (Brady et al., 2008; Bryers, 2008). As matter of fact, the eradication of bacterial biofilm by administration of antibiotics often fails due to the high drug resistance of bacteria in this lifestyle. Since 2008, European Centre for Disease Prevention and Control reports epidemiological data on the increasing of antimicrobial resistance constituting an important concern in public health hazard. For this reason, rapid assays to determine biofilm susceptibility to antibacterial drugs can significantly improve the outcome of infected patients by enabling a fast selection of efficient antibiotic treatments, thus decreasing the period and the related costs of hospitalization, as well as the incidence of morbidity and mortality ( Gfeller et al., 2005). Therefore, a fundamental prerequisite in studying, counteracting and eradicating biofilm is the possibility to quantify the actual number of bacteria involved. Bacterial counts have deep implications in microbiological diagnosis and therapeutic treatments (Bryers, 2008), in water and food quality analysis (Ramalho et al., 2001; Lee et al., 2007; Rueckert et al., 2005), in environmental applications and consumers’ safety. The standard method used to evaluate the number of bacteria, based on determination of Colony Forming Units (CFUs) (ISO method), can be considered fully appropriate only when bacteria are in planktonic lifestyle but it is unreliable to count bacteria in aggregated, adherent and biofilm lifestyle (Berlutti et al., 2003, Pantanella, 2008; Berlutti, 2008 a; Frioni,